No 1 - 2012

Infectious diseases 2011

Sprouts and other vegetables as a source of foodborne infection

The most serious outbreak of verocytotoxin-producing Escherichia coli (VTEC) infection in Europe to date occurred in May/June 2011. According to the Robert Koch Institute, the outbreak counted a total of 909 cases of haemolytic-uraemic syndrome (HUS), 3,070 VTEC cases and caused a total of 55 deaths. Most cases were observed in Northern Germany, but travel-related cases were seen in 15 other countries.

Denmark recorded a total of 26 cases, including ten with HUS, EPI-NEWS 27-33/11.

Independently of the German outbreak, an outbreak in France was caused by the same bacterium. Through comprehensive and complicated investigation, fresh fenugreek sprouts were identified as the source of the outbreak in both countries. The seeds used to produce the sprouts had been imported from a single Egyptian producer. In many cases, the sprouts had been used as decoration and in sandwiches, and many patients were consequently unaware that they had ingested the sprouts. Statens Serum Institut's contribution to the outbreak work was essential, among others with regard to characterizing the outbreak strain, determining the incubation period and identifying the source of infection. The outbreak strain, VTEC O104:H4 differs from most VTEC strains as its origin is a particular group of diarrhoeagenic E. coli, enteroaggregative E. coli. Furthermore, the bacterium took up genes for the production of verocytotoxin and antibiotic resistance. It is probable that these genetic properties made the strain more virulent than other frequently observed VTEC strains.

Vegetable sprouts are a well-known source of food-borne outbreaks. It is expected that the future will bring more outbreaks associated with fresh vegetables, herbs, sprouts and berries. The Salmonella Strathcona outbreak in September-October of 2011 is an additional example of this. A total of 40 Danes fell ill due to imported tomatoes. The increased importance of fruit and vegetables as a source of infection is associated with the continual import of vegetables from all parts of the world and with the fact that these are frequently ingested without prior heat treatment. Furthermore, the occurrence of food-borne bacteria in animal products such as meat and eggs is generally decreasing.

Measles

In 2011, many European countries including France, Spain, Germany, England and Switzerland reported a high occurrence of measles. Denmark saw a total of 83 cases. Most cases were from the Capital Region of Denmark (56) and Region Zealand (22), EPI-NEWS 24 and 35b/11. The outbreak counted more cases than any other in the past 15 years, reflecting that too many children, adolescents and young adults have not received the MMR vaccination. The 2011 situation shows that even in Western Europe, reaching the WHO's declared objective of eliminating measles by 2015 will be a considerable challenge.

Vaccination is a safe and simple method by which diseases that may have serious consequences can be prevented. It is therefore important that all health care professionals assist in supporting the childhood vaccination programme.

Change in the epidemiology of meningococcal disease

Once the final numbers are calculated, 2011 is expected to bring about 45 notifications of meningococcal disease (MD) caused by Neisseria meningitidis group C. In 2010, a total of 26 cases were reported, EPI-NEWS 37/11.

In 2000-2009, the mean annual number of MD cases caused by group C was 20. The development is equivalent to an increase in group C MD exceeding 70% in a single year. The highest increase was observed in children below the age of two years. The current trend in meningococcal group C disease is not due to outbreaks as all reported cases were sporadic. Concurrently with the increase in group C cases, the number of cases caused by group B MD has decreased to the lowest levels seen since monitoring was initiated in 1980.

Meningococcal disease is a serious infectious illness. It most frequently manifests as meningitis, sepsis or both. Currently, for 2011 a total of four deaths have been recorded in adults after MD caused by group C, corresponding to a 10% case-fatality in line with the fatality of the cases of group C disease recorded in the 2000-2010 period (9%). Due to the change in the epidemiology of meningococcal disease, 2011 will be the first year since monitoring was initiated in 1980 with more cases caused by meningococcal group C than by group B.

The distribution of meningococcal disease types is monitored by the SSI Reference Laboratory. In 2011, approx. 70% of the group C cases were of the phenotype 2A; P1.2, P1.2.5, P1.5 and of the genotype 5.2 F3-3. This type has been known in Denmark for a long time, but has only caused a few annual cases. The type, which is known to be associated with an increased risk of death after MD, is now the most commonly observed type. In several EU countries, it was an increase in the occurrence of invasive MD caused by this particular hyperinvasive and virulent type that led to the introduction of a vaccination programme against group C meningococci. With the increase in group C disease, Denmark is approaching the level which led to the introduction of vaccination against group C meningococci in several countries' childhood vaccination programmes, including Holland, England, Ireland, Iceland and Spain. The countries introducing the vaccine have observed a considerable decrease in the incidence of MD caused by group C briefly after the vaccine was introduced.

Antibiotic resistance

The majority of physicians (and patients) expect that bacterial infections may be managed efficiently with antibiotics. If bacteria develop resistance, it is expected that alternative and equally efficient drugs will be produced. This, however, is no longer necessarily the case. The spreading of carpapenemase-producing gram-negative bacteria, in particular, is rendering ineffective some critically important antibiotics, EPI-NEWS 44/11. This trend can and must be turned around. In connection with the Danish EU presidency, the fight against antibiotic resistance is a focus area. Efforts will e.g. be made to collect better data on antibiotic consumption and resistance, rational use of antibiotics and to reduce the use of critically important antibiotics for humans and animals. The Danish government wishes to contribute to the implementation of a concrete and cross-disciplinary policy in this area.

With this optimistic expectation, the Department of Epidemiology wishes all readers of EPI-NEWS a happy new year.
(K. Mølbak, Department of Epidemiology)

4 January 2012